"They don't realise they're flying to countries that not so long ago were classed as Third World."

Of those questioned in the survey - people who had returned from countries where vaccinations are required - a third had been to Asia, 29% to Africa, 21% to the Caribbean, 17% to the Far East and 15% to the Middle East.

Researchers have called for better travel health advice to be given, and say each patient's vaccination history should be recorded.

Advice

Despite the huge increase in the numbers of British holidaymakers choosing to go to exotic destinations, many do not know they need to seek health advice.

Only two thirds of those surveyed had sought advice about what vaccinations they needed.

The public can be complacent and nobody thinks it will happen to them, but it does

Carolyn DriverBritish Travel Health Association

Many who had been vaccinated could not remember what they had been given or how long the jabs lasted.

Of those who had, a quarter did not know they needed vaccinations, and 15% believed family or travel agents who said vaccinations were not necessary.

Holiday illnesses can range from diarrhoea and vomiting to Hepatitis A and typhoid - which can all be caused by contaminated food and water.

Hepatitis A causes inflammation of the liver and can cause sufferers months of agony.

But half of those surveyed did not know how it was transmitted.

Forty-five per cent are unaware of the effects of typhoid, which causes fever and abdominal pain.

But travellers do not appear to take the recommended precautions.

In the survey, 52% had ice in their drinks, 45% used tap water and 28% bought food from stalls on the street.

Caution

Dr Higson added: "We're so used to a relatively good standard of hygiene, we assume everywhere is the same."

He estimated a course of vaccinations could cost up to £50, but said many GP practices would give them for free.

He warned travellers to drink bottled water and introduce their stomachs to local cuisine gradually.

Carolyn Driver, travel health specialist nurse and chair of the British Travel Health Association, said: "Too many people are still disregarding their health by not getting the vaccines and advice they need.

"The public can be complacent and nobody thinks it will happen to them, but it does."

She said anyone who was going abroad should make sure they saw their GP or practice nurse well before they planned to travel, so they could have the right vaccinations.